I'm having a trouble with a mobile addon: it shows me the new elements added by scripting with a different charset of the page. E.g. I can read "cuadrúpedo" but the same word in my plugin show "cuadr¡pedo".
I tryed writing the next line to the beginning of my addon, but it didn't work:
document.getElementsByTagName("html")[0].setAttribute("lang", "es");
Then, I wrote a "converter function" which replaces the special characters with unicode, like the next line, but it didn't work.
str.replace( /ú/g, "/xfa־" );
What can I do?
Probably it's a matter of text encoding.
Make sure the file that contains the literal "cuadrúpedo" is saved as utf-8, not ansi.
Keep in mind that a few key files must be ansi encoded. These are install.rdf, chrome.manifest and bootstrap.js. In this case use unicode escapes, "cuadr\u00fapedo".
When the JavaScript file is loaded (in Gecko 1.8 and later) from a chrome:// URL, a Byte Order Mark is used to determine the character encoding of the script. Otherwise, the character encoding will be the same as the one used by the XUL file. So, one solution is the HTTP header can contain a character encoding declaration as part of the Content-Type header, for example:
Content-Type: application/javascript; charset=UTF-8
For cross version compatibility you must limit yourself to ASCII. However, you can use unicode escapes – the earlier example rewritten using them would be:
var text = "Ein sch\u00F6nes Beispiel eines mehrsprachigen Textes: \u65E5\u672C\u8A9E";
JavaScript and Navigator support for UTF-8/Unicode means you can use non-Latin, international, and localized characters, plus special technical symbols in JavaScript programs. Unicode provides a standard way to encode multilingual text: since the UTF-8 encoding of Unicode is compatible with ASCII, programs can use ASCII characters. To receive non-ASCII character input, the client needs to send the input as Unicode.
There is a webpage for text escaping and unescaping in Javascript:
http://0xcc.net/jsescape/
Sources:
https://developer.mozilla.org/en-US/docs/International_characters_in_XUL_JavaScript
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Values,_variables,_and_literals#Unicode
I'm using the mini_fb gem in ruby to create an ad group:
response = fb_ads.create_ad_groups_with_image('adgroup_specs' => adgroup_specs)
If the ad text contains certain characters, such as ∑, this fails with the following error:
The text contains an invalid character. Ads may only contain alphanumeric characters, punctuation, and spaces. Note that line breaks and = are not allowed.
However, there are many other characters, such as π, ö é, î, ä, å, ç, è, and ø, that are accepted just fine. Is there a list somewhere of what characters Facebook accepts in its ads, or a quick API call that I can make to check whether a string will pass?
The Facebook Ads system allows ad titles and body text in most languages around the world. However the symbol you've pasted in above is in a Unicode range dedicated to mathematical symbols. It isn't allowed in the body or title of a Facebook ad. The character you entered (Unicode U2211) has a good alternate in the Greek alphabet range of Unicode at U03A3. Entering HTML entities is not going to render like you want.
I don't have a link for you, but it is very likely that Facebook only supports/allows extended ASCII characters in their ads. That would include the characters you listed, but the "sum" character you listed is not within extended ascii. Have you tried using html entities for the "special" characters you need?
Why doesn't URI.escape escape single quotes?
URI.escape("foo'bar\" baz")
=> "foo'bar%22%20baz"
For the same reason it doesn't escape ? or / or :, and so forth. URI.escape() only escapes characters that cannot be used in URLs at all, not characters that have a special meaning.
What you're looking for is CGI.escape():
require "cgi"
CGI.escape("foo'bar\" baz")
=> "foo%27bar%22+baz"
This is an old question, but the answer hasn't been updated in a long time. I thought I'd update this for others who are having the same problem. The solution I found was posted here: use ERB::Util.url_encode if you have the erb module available. This took care of single quotes & * for me as well.
CGI::escape doesn't escape spaces correctly (%20) versus plus signs.
According to the docs, URI.escape(str [, unsafe]) uses a regexp that matches all symbols that must be replaced with codes. By default the method uses REGEXP::UNSAFE. When this argument is a String, it represents a character set.
In your case, to modify URI.escape to escape even the single quotes you can do something like this ...
reserved_characters = /[^a-zA-Z0-9\-\.\_\~]/
URI.escape(YOUR_STRING, reserved_characters)
Explanation: Some info on the spec ...
All parameter names and values are escaped using the [rfc3986]
percent- encoding (%xx) mechanism. Characters not in the unreserved
character set ([rfc3986] section 2.3) must be encoded. characters in
the unreserved character set must not be encoded. hexadecimal
characters in encodings must be upper case. text names and values must
be encoded as utf-8 octets before percent-encoding them per [rfc3629].
I know this has been answered, but what I wanted was something slightly different, and I thought I might as well post it up: I wanted to keep the "/" in the url, but escape all the other non-standard characters. I did it thus:
#public filename is a *nix filepath,
#like `"/images/isn't/this a /horrible filepath/hello.png"`
public_filename.split("/").collect{|s| ERB::Util.url_encode(s)}.join("/")
=> "/images/isn%27t/this%20a%20/horrible%20filepath/hello.png"
I needed to escape the single quote as I was writing a cache invalidation for AWS Cloudfront, which didn't like the single quotes and expected them to be escaped. The above should make a uri which is more safe than the standard URI.escape but which still looks like a URI (CGI Escape breaks the uri format by escaping "/").
Which characters make a URL invalid?
Are these valid URLs?
example.com/file[/].html
http://example.com/file[/].html
In general URIs as defined by RFC 3986 (see Section 2: Characters) may contain any of the following 84 characters:
ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-._~:/?#[]#!$&'()*+,;=
Note that this list doesn't state where in the URI these characters may occur.
Any other character needs to be encoded with the percent-encoding (%hh). Each part of the URI has further restrictions about what characters need to be represented by an percent-encoded word.
The '[' and ']' in this example are "unwise" characters but still legal. If the '/' in the []'s is meant to be part of file name then it is invalid since '/' is reserved and should be properly encoded:
http://example.com/file[/].html
To add some clarification and directly address the question above, there are several classes of characters that cause problems for URLs and URIs.
There are some characters that are disallowed and should never appear in a URL/URI, reserved characters (described below), and other characters that may cause problems in some cases, but are marked as "unwise" or "unsafe". Explanations for why the characters are restricted are clearly spelled out in RFC-1738 (URLs) and RFC-2396 (URIs). Note the newer RFC-3986 (update to RFC-1738) defines the construction of what characters are allowed in a given context but the older spec offers a simpler and more general description of which characters are not allowed with the following rules.
Excluded US-ASCII Characters disallowed within the URI syntax:
control = <US-ASCII coded characters 00-1F and 7F hexadecimal>
space = <US-ASCII coded character 20 hexadecimal>
delims = "<" | ">" | "#" | "%" | <">
The character "#" is excluded because it is used to delimit a URI from a fragment identifier. The percent character "%" is excluded because it is used for the encoding of escaped characters. In other words, the "#" and "%" are reserved characters that must be used in a specific context.
List of unwise characters are allowed but may cause problems:
unwise = "{" | "}" | "|" | "\" | "^" | "[" | "]" | "`"
Characters that are reserved within a query component and/or have special meaning within a URI/URL:
reserved = ";" | "/" | "?" | ":" | "#" | "&" | "=" | "+" | "$" | ","
The "reserved" syntax class above refers to those characters that are allowed within a URI, but which may not be allowed within a particular component of the generic URI syntax. Characters in the "reserved" set are not reserved in all contexts. The hostname, for example, can contain an optional username so it could be something like ftp://user#hostname/ where the '#' character has special meaning.
Here is an example of a URL that has invalid and unwise characters (e.g. '$', '[', ']') and should be properly encoded:
http://mw1.google.com/mw-earth-vectordb/kml-samples/gp/seattle/gigapxl/$[level]/r$[y]_c$[x].jpg
Some of the character restrictions for URIs and URLs are programming language-dependent. For example, the '|' (0x7C) character although only marked as "unwise" in the URI spec will throw a URISyntaxException in the Java java.net.URI constructor so a URL like http://api.google.com/q?exp=a|b is not allowed and must be encoded instead as http://api.google.com/q?exp=a%7Cb if using Java with a URI object instance.
Most of the existing answers here are impractical because they totally ignore the real-world usage of addresses like:
https://en.wikipedia.org/wiki/Möbius_strip or
https://zh.wikipedia.org/wiki/Wikipedia:关于中文维基百科/en.
First, a digression into terminology. What are these addresses? Are they valid URLs?
Historically, the answer was "no". According to RFC 3986, from 2005, such addresses are not URIs (and therefore not URLs, since URLs are a type of URIs). Per the terminology of 2005 IETF standards, we should properly call them IRIs (Internationalized Resource Identifiers), as defined in RFC 3987, which are technically not URIs but can be converted to URIs simply by percent-encoding all non-ASCII characters in the IRI.
Per modern spec, the answer is "yes". The WHATWG Living Standard simply classifies everything that would previously be called "URIs" or "IRIs" as "URLs". This aligns the specced terminology with how normal people who haven't read the spec use the word "URL", which was one of the spec's goals.
What characters are allowed under the WHATWG Living Standard?
Per this newer meaning of "URL", what characters are allowed? In many parts of the URL, such as the query string and path, we're allowed to use arbitrary "URL units", which are
URL code points and percent-encoded bytes.
What are "URL code points"?
The URL code points are ASCII alphanumeric, U+0021 (!), U+0024 ($), U+0026 (&), U+0027 ('), U+0028 LEFT PARENTHESIS, U+0029 RIGHT PARENTHESIS, U+002A (*), U+002B (+), U+002C (,), U+002D (-), U+002E (.), U+002F (/), U+003A (:), U+003B (;), U+003D (=), U+003F (?), U+0040 (#), U+005F (_), U+007E (~), and code points in the range U+00A0 to U+10FFFD, inclusive, excluding surrogates and noncharacters.
(Note that the list of "URL code points" doesn't include %, but that %s are allowed in "URL code units" if they're part of a percent-encoding sequence.)
The only place I can spot where the spec permits the use of any character that's not in this set is in the host, where IPv6 addresses are enclosed in [ and ] characters. Everywhere else in the URL, either URL units are allowed or some even more restrictive set of characters.
What characters were allowed under the old RFCs?
For the sake of history, and since it's not explored fully elsewhere in the answers here, let's examine was allowed under the older pair of specs.
First of all, we have two types of RFC 3986 reserved characters:
:/?#[]#, which are part of the generic syntax for a URI defined in RFC 3986
!$&'()*+,;=, which aren't part of the RFC's generic syntax, but are reserved for use as syntactic components of particular URI schemes. For instance, semicolons and commas are used as part of the syntax of data URIs, and & and = are used as part of the ubiquitous ?foo=bar&qux=baz format in query strings (which isn't specified by RFC 3986).
Any of the reserved characters above can be legally used in a URI without encoding, either to serve their syntactic purpose or just as literal characters in data in some places where such use could not be misinterpreted as the character serving its syntactic purpose. (For example, although / has syntactic meaning in a URL, you can use it unencoded in a query string, because it doesn't have meaning in a query string.)
RFC 3986 also specifies some unreserved characters, which can always be used simply to represent data without any encoding:
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-._~
Finally, the % character itself is allowed for percent-encodings.
That leaves only the following ASCII characters that are forbidden from appearing in a URL:
The control characters (chars 0-1F and 7F), including new line, tab, and carriage return.
"<>^`{|}
Every other character from ASCII can legally feature in a URL.
Then RFC 3987 extends that set of unreserved characters with the following unicode character ranges:
%xA0-D7FF / %xF900-FDCF / %xFDF0-FFEF
/ %x10000-1FFFD / %x20000-2FFFD / %x30000-3FFFD
/ %x40000-4FFFD / %x50000-5FFFD / %x60000-6FFFD
/ %x70000-7FFFD / %x80000-8FFFD / %x90000-9FFFD
/ %xA0000-AFFFD / %xB0000-BFFFD / %xC0000-CFFFD
/ %xD0000-DFFFD / %xE1000-EFFFD
These block choices from the old spec seem bizarre and arbitrary given the latest Unicode block definitions; this is probably because the blocks have been added to in the decade since RFC 3987 was written.
Finally, it's perhaps worth noting that simply knowing which characters can legally appear in a URL isn't sufficient to recognise whether some given string is a legal URL or not, since some characters are only legal in particular parts of the URL. For example, the reserved characters [ and ] are legal as part of an IPv6 literal host in a URL like http://[1080::8:800:200C:417A]/foo but aren't legal in any other context, so the OP's example of http://example.com/file[/].html is illegal.
In your supplementary question you asked if www.example.com/file[/].html is a valid URL.
That URL isn't valid because a URL is a type of URI and a valid URI must have a scheme like http: (see RFC 3986).
If you meant to ask if http://www.example.com/file[/].html is a valid URL then the answer is still no because the square bracket characters aren't valid there.
The square bracket characters are reserved for URLs in this format: http://[2001:db8:85a3::8a2e:370:7334]/foo/bar (i.e. an IPv6 literal instead of a host name)
It's worth reading RFC 3986 carefully if you want to understand the issue fully.
All valid characters that can be used in a URI (a URL is a type of URI) are defined in RFC 3986.
All other characters can be used in a URL provided that they are "URL Encoded" first. This involves changing the invalid character for specific "codes" (usually in the form of the percent symbol (%) followed by a hexadecimal number).
This link, HTML URL Encoding Reference, contains a list of the encodings for invalid characters.
Several of Unicode character ranges are valid HTML5, although it might still not be a good idea to use them.
E.g., href docs say http://www.w3.org/TR/html5/links.html#attr-hyperlink-href:
The href attribute on a and area elements must have a value that is a valid URL potentially surrounded by spaces.
Then the definition of "valid URL" points to http://url.spec.whatwg.org/, which says it aims to:
Align RFC 3986 and RFC 3987 with contemporary implementations and obsolete them in the process.
That document defines URL code points as:
ASCII alphanumeric, "!", "$", "&", "'", "(", ")", "*", "+", ",", "-", ".", "/", ":", ";", "=", "?", "#", "_", "~", and code points in the ranges U+00A0 to U+D7FF, U+E000 to U+FDCF, U+FDF0 to U+FFFD, U+10000 to U+1FFFD, U+20000 to U+2FFFD, U+30000 to U+3FFFD, U+40000 to U+4FFFD, U+50000 to U+5FFFD, U+60000 to U+6FFFD, U+70000 to U+7FFFD, U+80000 to U+8FFFD, U+90000 to U+9FFFD, U+A0000 to U+AFFFD, U+B0000 to U+BFFFD, U+C0000 to U+CFFFD, U+D0000 to U+DFFFD, U+E1000 to U+EFFFD, U+F0000 to U+FFFFD, U+100000 to U+10FFFD.
The term "URL code points" is then used in the statement:
If c is not a URL code point and not "%", parse error.
in a several parts of the parsing algorithm, including the schema, authority, relative path, query and fragment states: so basically the entire URL.
Also, the validator http://validator.w3.org/ passes for URLs like "你好", and does not pass for URLs with characters like spaces "a b"
Of course, as mentioned by Stephen C, it is not just about characters but also about context: you have to understand the entire algorithm. But since class "URL code points" is used on key points of the algorithm, it that gives a good idea of what you can use or not.
See also: Unicode characters in URLs
I needed to select characters to split URLs in a string, so I decided to create a list of characters which could not be found in the URL by myself:
>>> allowed = "-_.~!*'();:#&=+$,/?%#[]?#ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
>>> from string import printable
>>> ''.join(set(printable).difference(set(allowed)))
'`" <\x0b\n\r\x0c\\\t{^}|>'
So, the possible choices are the newline, tab, space, backslash and "<>{}^|. I guess I'll go with the space or newline. :)
I am implementing an old HTTP (0.9, 1.0, 1.1) request and response reader/writer. The request URI is the most problematic place.
You can't just use RFC 1738, 2396 or 3986 as it is. There are many old HTTP clients and servers that allow more characters. So I've made research based on accidentally published web server access logs: "GET URI HTTP/1.0" 200.
I've found that the following non-standard characters are often used in URIs:
\ { } < > | ` ^ "
These characters were described in RFC 1738 as unsafe.
If you want to be compatible with all old HTTP clients and servers - you have to allow these characters in the request URI.
Please read more information about this research in oghttp-request-collector.
This is not really an answer to your question, but validating URLs is really a serious p.i.t.a. You're probably just better off validating the domain name and leave query part of the URL be. That is my experience.
You could also resort to pinging the URL and seeing if it results in a valid response, but that might be too much for such a simple task.
Regular expressions to detect URLs are abundant, google it :)
I can't comment on the above answers, but wanted to emphasize the point (in another answer) that allowed characters aren't allowed everywhere. For example, domain names can't have underscores, so http://test_url.com is invalid.
From the source (emphasis added when needed):
Unsafe:
Characters can be unsafe for a number of reasons. The space character is unsafe because significant spaces may disappear and insignificant spaces may be introduced when URLs are transcribed or typeset or subjected to the treatment of word-processing programs.
The characters "<" and ">" are unsafe because they are used as the
delimiters around URLs in free text; the quote mark (""") is used to
delimit URLs in some systems. The character "#" is unsafe and should
always be encoded because it is used in World Wide Web and in other
systems to delimit a URL from a fragment/anchor identifier that might
follow it. The character "%" is unsafe because it is used for
encodings of other characters. Other characters are unsafe because
gateways and other transport agents are known to sometimes modify such
characters. These characters are "{", "}", "|", "", "^", "~", "[",
"]", and "`".
All unsafe characters must always be encoded within a URL. For
example, the character "#" must be encoded within URLs even in systems
that do not normally deal with fragment or anchor identifiers, so that
if the URL is copied into another system that does use them, it will
not be necessary to change the URL encoding.
Source
I came up with a couple of regular expressions for PHP that will convert URLs in text to anchor tags. (First it converts all www. URLs to http://, and then converts all URLs with https?:// to a href=... HTML links
$string = preg_replace('/(https?:\/\/)([!#$&-;=?\-\[\]_a-z~%]+)/sim', '$2', preg_replace('/(\s)((www\.)([!#$&-;=?\-\[\]_a-z~%]+))/sim', '$1http://$2', $string) );